Calibration Points of Pt100 Thermocouple Temperature Sensor
Selection and verification methods of calibration points of pt100 thermocouple temperature sensor:
Pt100 calibration point selection and basic methods:
1. The calibration points of each grade of Pt100 should be 0℃ and 100℃, and the compliance of the actual resistance temperature coefficient a should be checked;
2. When △a does not meet the requirements, the temperature verification should be performed at the upper (or lower) limit of the effective temperature range of the corresponding tolerance level in Table 1;
3. The resistance value measurement of Pt100 and second-class standard platinum resistance thermometer should adopt the four-wire measurement method;
4. When calibrating Pt100, the current through the thermal resistor should not be greater than 1mA, and a digital multimeter that meets the measurement accuracy requirements should be used. The platinum resistance method is repeated alternately no less than 4 times (including current reversal), and the average value is taken as the measurement result.
Verification of R0 (resistance value when the temperature is 0℃)
1. In a freezing point bath (or a constant temperature bath with 0°C, the deviation does not exceed ±0.2°C), measure the resistance value of Pt100 and the temperature measured by a second-class standard platinum resistance thermometer, and compare and calculate the deviation value of 0°C ± △t0;
2. The thermal resistor with a removable protective tube should be placed in a glass test tube with an inner diameter slightly larger than the diameter of the temperature sensing element. After the mouth of the tube is plugged tightly with absorbent cotton or a wooden plug, insert it into a freezing point tank where ice water is fully mixed. The insertion depth should be no less than 30mm;
3. The non-detachable Pt100 thermal resistor with protective tube can be directly inserted into the medium. During calibration, readings can only be made when the measurement data is stable;
4. If a 0℃ constant temperature bath is used, the Pt100 thermal resistor should have sufficient insertion depth to reduce heat loss as much as possible;
5. To calibrate Pt100 thermal resistors of grade AA or above, in order to reduce the test uncertainty, it is advisable to measure in a water triple point bottle.
Verification of R100 (resistance value at temperature 100°C) and Rt (resistance value at temperature t°C)
1. Measure the resistance value of the Pt100 thermal resistor R100 in a constant temperature bath at 100°C, compare it with the temperature measured by a second-class standard platinum resistance thermometer, and calculate the deviation value Δt100 at 100°C;
2. The Rt calibration of the detachable Pt100 thermal resistor is the same as the R0 calibration. Place the temperature-sensing element in a glass test tube (when the calibration temperature is higher than 400°C, it should be placed in a quartz test tube);
3. Insert into the constant temperature bath and ensure sufficient insertion depth. After thermal equilibrium, continue to increase the insertion depth by 10mm. The change in resistance value after re-reaching thermal equilibrium should not exceed 5% of the allowable error;
4. When the temperature t is higher than 500°C, the thermal resistor should be cooled to 0°C in the tank at a rate of less than 1°C/min before being taken out of the temperature control tank;
5. The calibration point temperature of the constant temperature bath should not exceed ±2℃, and the change within 10 minutes should not exceed ±0.02℃.
Industrial Pt100 thermal resistance allowable error table
Qualification judgment of R0 and R100 resistance values
1. Within the effective temperature range, the maximum deviation between the temperature t calculated by the graduation table and the true temperature of the thermal resistor resistance value should not exceed the tolerance value given in the table above.
2. The nominal values of Pt100 (a platinum resistor with a resistance value of 100 at 0°C) and Cu100 (a copper resistor with a resistance value of 100 at 0°C) and the ranges of R0 and R100 that meet the tolerance requirements are shown in the table below.
Pt100 calibration point selection and basic methods:
1. The calibration points of each grade of Pt100 should be 0℃ and 100℃, and the compliance of the actual resistance temperature coefficient a should be checked;
2. When △a does not meet the requirements, the temperature verification should be performed at the upper (or lower) limit of the effective temperature range of the corresponding tolerance level in Table 1;
3. The resistance value measurement of Pt100 and second-class standard platinum resistance thermometer should adopt the four-wire measurement method;
4. When calibrating Pt100, the current through the thermal resistor should not be greater than 1mA, and a digital multimeter that meets the measurement accuracy requirements should be used. The platinum resistance method is repeated alternately no less than 4 times (including current reversal), and the average value is taken as the measurement result.
1. In a freezing point bath (or a constant temperature bath with 0°C, the deviation does not exceed ±0.2°C), measure the resistance value of Pt100 and the temperature measured by a second-class standard platinum resistance thermometer, and compare and calculate the deviation value of 0°C ± △t0;
2. The thermal resistor with a removable protective tube should be placed in a glass test tube with an inner diameter slightly larger than the diameter of the temperature sensing element. After the mouth of the tube is plugged tightly with absorbent cotton or a wooden plug, insert it into a freezing point tank where ice water is fully mixed. The insertion depth should be no less than 30mm;
3. The non-detachable Pt100 thermal resistor with protective tube can be directly inserted into the medium. During calibration, readings can only be made when the measurement data is stable;
4. If a 0℃ constant temperature bath is used, the Pt100 thermal resistor should have sufficient insertion depth to reduce heat loss as much as possible;
5. To calibrate Pt100 thermal resistors of grade AA or above, in order to reduce the test uncertainty, it is advisable to measure in a water triple point bottle.
Verification of R100 (resistance value at temperature 100°C) and Rt (resistance value at temperature t°C)
1. Measure the resistance value of the Pt100 thermal resistor R100 in a constant temperature bath at 100°C, compare it with the temperature measured by a second-class standard platinum resistance thermometer, and calculate the deviation value Δt100 at 100°C;
2. The Rt calibration of the detachable Pt100 thermal resistor is the same as the R0 calibration. Place the temperature-sensing element in a glass test tube (when the calibration temperature is higher than 400°C, it should be placed in a quartz test tube);
3. Insert into the constant temperature bath and ensure sufficient insertion depth. After thermal equilibrium, continue to increase the insertion depth by 10mm. The change in resistance value after re-reaching thermal equilibrium should not exceed 5% of the allowable error;
4. When the temperature t is higher than 500°C, the thermal resistor should be cooled to 0°C in the tank at a rate of less than 1°C/min before being taken out of the temperature control tank;
5. The calibration point temperature of the constant temperature bath should not exceed ±2℃, and the change within 10 minutes should not exceed ±0.02℃.
Industrial Pt100 thermal resistance allowable error table
Qualification judgment of R0 and R100 resistance values
1. Within the effective temperature range, the maximum deviation between the temperature t calculated by the graduation table and the true temperature of the thermal resistor resistance value should not exceed the tolerance value given in the table above.
2. The nominal values of Pt100 (a platinum resistor with a resistance value of 100 at 0°C) and Cu100 (a copper resistor with a resistance value of 100 at 0°C) and the ranges of R0 and R100 that meet the tolerance requirements are shown in the table below.
